1. Field of the Invention
The invention relates generally to the field of media presentation, and more particularly to methods and apparatus for synchronizing media files.
2. Background Information
A mixed-media file presentation system is a presentation system that simultaneously presents different media elements, such as video, audio, images, and text. FIG. 1 illustrates such a mixed-media file presentation system as the display screen of a computer, which is one means for delivering a mixed-media file presentation. The mixed-media file presentation system of FIG. 1 comprises a frame and background 106 that hold a variety of media elements. In this particular example, there is a video element 100, a static image element 102, and a text element 104 in the form of subtitles. When the mixed-media file presentation system is in use, the video plays while the slides and subtitles change. The system may also present animations or simulations.
In order for the mixed-media presentation to flow smoothly, it is necessary to synchronize the different media elements so that they will be presented at the correct moment in the presentation. For instance, the presentation can consist of a video of a person giving a lecture, slides to which the lecturer refers, and subtitles that display what the lecturer is saying in any of a number of languages.
The presentation system must display the slides at the correct moment in the lecture, and it must correctly present subtitles while the video is playing. The presentation must correctly associate these media elements to one another.
According to the present state-of-the-art, methods exist for achieving this type of synchronization. In a known embodiment, data is physically embedded for the slides and subtitles into the actual video data file. For example, a user will embed Universal Record Locators (“URLs”) at locations within the video data file that are links to the slides or subtitles, or the user will place URLs at the front of the video data file and embed markers into the video data file at various locations in the data stream. The embedded URLs or markers appear at locations in the video data file that correspond to when the slides and subtitles are to appear.
A drawback to the above approach is that it is destructive and therefore makes reuse of the files a problem. By stating that this method is destructive, it is meant that it permanently changes the video data file (for instance). Later, if it is desired to reuse some portion of the previous files, then the user must start from scratch and embed new data into a fresh video data file.
Notwithstanding the destructive nature of such a system, the method for making changes to a mixed-media file presentation system discussed above is time-consuming and tedious: users often must carefully watch and time a video as it plays to know where to embed the slide and subtitle data.